Catalytic desulfurization of petroleum hydrocarbons



Oct. 20, 1953 F. w. B. PORTER ETAL 1 2,656,302

CATALYTIC DESULFURIZATION OF PETROLEUM HYDROCARBONS Filed Sept. 20, 1950 2 Sheets-Sheet 1 I v flydrqyen Pretreako' Cate/gs! g n f o Pemova/ 0 o /0 '20 a0 I0 Hours on .s'zl'eam In ven lorzs Frederick William Bertram Porter and John Norman Hareanapq t- 0,1953 'F. w. B. PORTER ET AL 2,656,302.

CATALYTIC DESULFURIZATION OF PETROLEUM HYDROCARBONS Filed Sept. 20,1950 v 2 Sheets-Sheet 2 /o v FEED"\ STOCK \/V\/\r Y F/G-Z. v

' LPREHEATER 1 Hvnnogllzgflsgkgnmg 25 I STEAM AND AIR FOR /REGENERATION w L 27 2 20 COOLER I SEPARATOR STABILIZER I 1 //COLUMN RLACTQR X 1' 1v /5 RECYCLE I I GAS 2! REGENERATIOM/ GASES 26 BOOSTER Inueniorfi Frederick William Bertram Porter and John Norman Haresnape Patented Oct. 20, 1953 I CATALYTIC DESULFURIZATION OF I PETROLEUM HYDROCARBONS Frederick William Bertram Porter and John Norman Harcsnape, Sunbury-on-Thames, England, assignors to Anglo-Iranian Oil Company Lim-' ited, London, England,

corporation a British joint-stock Application September 20, 1950, Serial No. 185,704

, InGreat Britain September 22, 1949 This invention relates to the catalytic desulphurisation of petroleum hydrocarbons.

Iii-the specifications of 'co-pending applications Nos; 35,976; 46,502 (now Patent No. 2,574,445); 68,416 (now Patent No. 2,574,446); 100,538 (now Patent No. 2,574A48); and 94,262 (now Patent No.2,5'74,447)" there are described processes for the catalytic desiilphurisation of petroleum fractions ranging from light distillates, such as light naphtha, to heavy distillates, such as wax distillate, wherein the feedstock is passed to a cataiytic desulphurisation zone wherein it is treated in the presence of a sulphur-resistant hydrogenation catalyst, as specified, under conditions of temperature and pressure such that sufficient hydrogen is produced by dehydrogenation of naphthene hydrocarbons contained in the feedstock to eiiect the conversion of sulphur compounds contained in the feedstock into hydrogen sulphide and to provide a hydrogen-rich gaseous 1.

fraction which is recycled to the catalytic desulphurisation zone in order to maintain the necessary partial pressure of hydrogen therein. Broadly, the basic autofining process outlined in the aforementioned applications and patents is operated by maintaining a selected temperature in the reactionzone between about 650 F, to about 800 F. at which hydrogen is continuously produced from the product and a selected pressure is maintained in thereaction zone between about,25, to about 250 lbs/sq. in; gauge. ,The selected temperature and pressure are correlated to provide, from the dehydrogenation of the naphthenes contained in the product, a net production of hydrogen at least sufficient to convert organic compounds present in the product to hydrogen sulphide. Such processes are carried out without the use of extraneous hydrogen and it is convenient .to designate such processes as autofming processes to distinguish them from similar catalytic desulphurisation processes 'carriedout with the aid of extraneous hydrogen, the latter processes being commonly called hydro.- fining processes. 7. a

In the specification of co-pending application Serial. No. 153,339 filed April 1, 1950 a further development of the autofining process was described in which, instead of setting the pressure in the autofining zone at a predetermined level and thereafter withdrawing from the system gas in excess of that required to maintain the predetermined pressure, the whole of the hydrogencontaining gaseous fraction separated from, the

said zone and the pressure therein allowedto 5 Claims." (01. 196-28) rise to an equilibrium pressure at which the hy ,drogen-e'volved equals the hydrogen consumed. Under these equilibrium process conditions a greater degree of desulphurisation is achieved, the on-stream hours for a product of given sulphur content are increased and the hydrogen produced in the hydrogenation reaction is fully utilised in the desulphurisation reaction.

In carrying out the autofining process, the preferred catalyst is of the so-called cobalt molybdate type which consists of the oxides of cobalt and molybdenum deposited on or incorporated with a support, preferably alumina. The unit is normally pressured up to operating pressure and gas recycle commenced, so as to bring the catalyst up to the operating temperature; To carry out this pretreatment requires the provi-'- sion of a considerable amount of hydrogen (of the order of 64 cufft. per cu. ft.of catalyst) which is used up by partial reduction of the cat alyst and by sorption on the catalyst itself. The hydrogen can be obtainedfrom the processprovided adequate storage factilities are provided.

Furthermore, it has been found that there is a period at'the commencement of each run during which the gas make is negligible or nonexistent and the desulphurisation is not at its maximum. This low dehydrogenating activity of the catalyst is more noticeable at low feedstock velocities and with the heavier type of feed stock.

It has now been" discovered that the autofining process may be operated in a manner which gives increased dehydrogenation and desulphurisation during the early hours on stream and whichconsumes considerably less hydrogen than hitherto for the purpose of pretreating the catalyst.

According to the invention, the autofining process for the catalytic desulphurisation of "a petroleum distillate, is carried out using a cataly'stconsisting of the combined oxides of cobalt and molybdenum deposited on or incorporated with a support, said catalyst having previously been subjected to treatment with hydrogen sulphide or hydrogen sulphide-containing gases.

The hydrogen sulphide used for the pre-treatment of the catalyst may consist of substantially pure hydrogen sulphide but may more conve'n 'i'ently consist of hydrogen sulphide-containing gases available from the autofining' process. Thus, in the autofining, process, the treated dise tillate is first cooled at plant pressure to separate the recycle gas containing a high proportion of hydrogen and a small proportion of HzS and the pmdu t, t erea er tab s d b n e ed or if desired, the HzS may be recovered from the:

stabiliser gas and used in substantially pure form.

In applying the autofining process'to' gas oils" and heavier fractions, two.or more reactors are. employed in order to provide=for-conti=nuous op eration, and in such method: of operation: i t-maya be convenient to carry out ..thepretreatment of.

the catalyst by passing stabiliser gas direct from the stabiliser through a reactor. immediately after the regenerating stage while.-the.-catalyst..

is still hot. Alternatively, the stabiliser gases may be collected under pressure and recycled-as desired.

The application-ofthe processot-the. inventionzto an autofiningsystem incorporating two reactors will nowbe-described with reference-to Figure 1- of the accompanying drawings.

The. feed is introduced through line H1 and after" passing through the preheater l-t enters oneofthereactors l-Z maintained under autofining conditions of temperature and. pressure; The product from the-:reaotor'passes. via line I3 to the cooler: M wherein it is cooled-under reactor pressure'and the liquified product passed toaseparatorl5-from which a recycle gas containing a high-proportion of hydrogen is removed; via line Hiand fed by means of-the-booster" I 'lx'into admixture with the 'preheated feed to the reactor; The liquefied productfrom: the separator: [5,; still containing the bulk of the hydrogen. sulphide' irr solution, is passed via line lBrto astabiliser'columnl9. The overhead gas from; the column 19 is-passed-via. cooler 20 B022, separator 2 I' from which hydrogen sulphide rich gas "is removed via line .22 and vented, while liquid'from the separator 2| is. returned via line 23-. as reflux: to thetop of the column. Hydrogen sulphide free product-is removed fromuthe base of the-column lflrvia. line 24.

While. one reactor lZ-is on stream; the-other reactor l2 is being regenerated, for which purposeamixture ofzsteam and air isadmitted via line the regeneration gases leaving via line 26. In accordance with the process of the in-. vention, immediatelyafter the-regeneration of azreactor. l2 is'completedand while the catalyst isstill hot; hydrogen sulphide rich. gas is passed through" the: reactor via lines. 25 and 21 and leavesv through-11inc- 2.6:. After the treatmentof the regenerated: catalysttwi-th the hydrogen sulphide-rich gashasrcontinued. for "a suitableetime, the: reactor-is; ready to; be. broughtwon stream again;

The. autofimng of: a. wax distillate by the PITOCESS'Of the invention. will now. be. described by way" of examplewith; reference to-the-. accompanying. graph, Figure; 2".

A; wax distillate consisting of the .fractionrdistilled: over between 55.7-86-.1% volume on' an Iraniancrude. oil and. having a 1 sulphur content of 1..74.-%-wt. was. subjected to twoseparatez auto.- fining operations" underthe following; operating conditions Catalyst Cobalt" molybdate on alumina.

Temperature 750 F;

Space velocity 0.5"v/v/hr.

Gas recycle rate 4000' CF73 at 100 prs. i. g'.

Both operations were carried out under equilibrium process conditions, i. e. the unit was shut in and allowed to find its own pressure level.

In: theafirst operation the reactor was pressured up to 100 p. s. i. g. and given the usual hydrogen pretreatment for half an hour before commencing. the feed. The second operation was.-carri'ed?out using the regenerated catalyst from the first operation. After the regeneration stage; thereactor was allowed to cool down to 400'-500 andihydrogen sulphide gas was recycled lat-.IOQ 137-5. i. g. pressure. After half an hour, the...pressurei had dropped to a steady 10 p. s. i. g. The unit was then depressurised and repressurediyvith'hydrogen to 100 p. s. i. g. After bringing the temperature up to the operating temperature, during which period no hydrogen was consumed, the feed was commenced.

Bwreterenceato the; accompanying graph, it will be seen that, using, therhydrogen preheated catalyst, the pressure-in the reactor. fell for. the first ten hoursand; didnot reach equilibrium pressure until 40 hours had elapsed. The desulphurisationafter 1-0- hourson stream was about'44%. Using thev presulphidedcatalyst, the pressure built up immediately andireached equilibrium pressure after 8l-9"hours:; After? 10 hours on stream the desulphurisation' was over We claim:

1. Ina continuous process for the'hyd-rocatalytic desulphurization of a sulphur-and-naphthene-con-taining hydrocarbon oil' wherein the oil is contacted in a reactiorrzone at an elevated temperature and pressurein the presence of hydrogen with a dehydrogenation-hydrogenation catalyst which" has been pretreated with hydrogen sulphide and which is-immune to sulphur poisoning and'combining activity for "the dehydrogenation of-naphthenes insaid oil to aromatics with activity for the hydrogenation of organicallycombined sulphur-in'the oilto hydrogen sulphide, the method of operating the proc ess so that it will be self-supporting with respect to the amount of hydrogemneeded' and give increased dehydrogenation and: desulphurization during the early hours on stream and consume considerably less hydrogen than heretofore required' for the purpose of pretreating the catalyst and produce a desulphurized' oil: comprising the steps of passi'ng the hydrocarbon oil to be treated through said fireaction zone. and contacting the oil therein with. hydrogen derived solely from the oil and with saidcatalyst which has been pretreated with hydrogen sulphide derivedsolely from the oil, said conditions of elevated temperature andpressurebeing such that sufli'cient hydrogenispmduced by, dehydrogenation of"naplrithenev hydrocarbonscontained in the oil'to. effect theconversion ofisulphur com? pounds contained in the oil into.hy drog,en,sul phide and to. provide. a hydrogen-rich gaseous mixture which is recycledto the catalytic desulphurization zonein order to maintainv the necessary. partial pressure. .of. hydrogen therein; passingthe, desulphurized oil to. agas separation stage maintained under. the desulphurization pressure but reducedtemperature, separate ing a hydrogen-rich gas mixture, and leaving a liquid product containing the bulk of the hydrogen-sulphide obtained from the reactionin solution, recycling said hydrogen-rich gas mixtureto-the reaction zone toconsti-tu-te the whole of the hydrogen supplied to said zone, passing said hydrogen-sulphide-containing liquid product to a stabilizing stage for the separation of a hydrogen-sulphide-rich gas, separately regenerating catalyst for use in said process, and passing said hydrogen-sulphide-rich gas back to the regenerating system for treating the catalyst in said regenerating system just after it has been regenerated.

2. A process in accordance with claim 1 wherein the catalyst consists of the combined. oxides of cobalt and molybdenum.

3. A process in accordance with claim 1 wherein the operating temperature is a selected temperature between about 650 F. to about 800 F. at which hydrogen is continuously produced from the oil and a selected pressure between about 25 to about 250 lbs/sq. in. gauge is maintained insaid reaction zone, said selected temperature and pressure being correlated to pro- 5. A process in accordance with claim 1 in which after a determined period of time the treatment of said oil is transferred to and continued in a second catalytic desulphurization zone, the spent catalyst in said first zone being regenerated in situ, and while the regenerated catalyst is still hot, pretreating the regenerated catalyst with hydrogen sulphide separated from the treated oil from said second zone, discontinuing the pretreating operation, bringing the hydrogen sulphide treated catalyst up from the pretreating temperature to the operating temperature in an atmosphere of hydrogen, and employing the regenerated and pretreated catalyst for the treatment of further quantities of said oil.

FREDERICK WILLIAM BERTRAM PORTER. JOHN NORMAN HARESNAPE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,105,665 Lazier et al. Jan. 18, 1938 2,131,089 Beeck et al. Sept. 27, 1938 2,325,033 Byrns July 27, 1943 2,431,920 Cole Dec. 2, 1947 2,567,252 Strang Sept; 11, 1951 2,574,445 Porter et al. Nov. 6, 195 1 

1. IN A CONTINOUS PROCESS FOR THE HYDROCATALYTIC DESULPHURIZATION OF A SULPHUR-AND-NAPHTHENE-CONTAINING HYDROCARBON OIL WHEREIN THE OIL IS CONTACTED IN A REACTION ZONE AT AN ELEVATED TEMPERATURE AND PRESSURE IN THE PRESENCE OF HYDROGEN WITH A DEHYDROGENATON-HYDROGENATION CATALYST WHICH HAS EEN PRETREATED WITH HYDROGEN SULPHIDE AND WHICH IS IMMUNE TO SULPHUR POISONING AND COMBINING ACTIVITY FOR THE DEHYDROGENATIN OF NAPHTHENES IN SAID OIL TO AROMATICS WITH ACTIVITY FOR THE HYDROGENATION OF ORGANICALLY COMBINED SULPHUR IN THE OIL TO HYDRO GEN SULPHIDE, THE METHOD OF OPERATING THE PROCESS SO THAT IT WILL BE SELF-SUPPORTING WITH RESPECT TO THE AMOUNT OF HYDROGEN NEEDED AND GIVE INCREASED DEHYDROENATION AND DESULPHURIZATION DURING THE EARLY HOURS ON STREAM AND CONSUME CONSIDERABLY LESS HYDROGEN THAN HEREFORE REQUIRED FOR THE PURPOSE OF PRETREATING THE CATALYST AND PRODUCE A DESULPHURIZED OIL; COMPRISSING THE STEPS OF PASSING THE HYDROCARBON OIL TO BE TREATED THROUGH SAID REACTION ZONE AND CONTACTING THE OIL THEREIN WITH HYDROGEN DERIVED SOLELY FROM THE OIL AND WITH SAID CATALYST WHICH HAS BEEN PRETREATED WITH HYDROGEN SULPHIDE DERIVED SOLELY FROM THE OIL, SAID CONDITIONS OF ELEVATED TEMPERATURE AND PRESSURE BEING SUCH THAT SUFFICIENT HYDROGEN IS PRODUCED BY DEHYDROGENATION OF NAPHTHENE HYDROCARBONS CONTAINED IN THE OIL TO EFFECT THE CONVERSIN OF SULPHUR COMPOUNDS CONTAINED I THE OIL HYDROGEN SULPHIDE AND TO PROVIDE A HYDROGEN-RICH GASEOUS MIXTURE WHICH IS RECYCLED TO THE CATALYTIC DESULPHURIZATION ZONE IN ORDER TO MAINTAIN THE NECESSARY PARTIAL PRESSURE OF HDROGEN THEREIN, PASSING THE DESULPHURIZED OIL TO A GAS SEPARATION STAGE MAINTAINED UNDER THE DESULPHURIZATIN PRESSURE BUT REDUCED TEMPERATURE, SEPARATING A HYDROGEN-RICH GAS MIXTURE, AND LEAVING A LIQUID PRODUCT CONTAINING THE BULK OF THE HYDROGEN-SULPHDE OBTAINED FROM THE REACTION IN SOLUTION, RECYCLING SAID HYDROGEN-RICH GAS MIXTURE TO THE REACTION ZONE TO CONSTITUTE THE WHOLE OF THE HYDROGEN SUPPLIED TO SAID ZONE, PASSING SAID HYDROGEN-SULPHIDE-CONTAINING LUQUID PRODUCT TO A STABILIZING STAGE FOR THE SEPARATION OF A HYDROGEN-SULPHIDE-RICH GAS, SEPARATELY REGENERATING CATALYST FOR USE IN SAID PROCESS, AND PASSING SAID HYDROGEN-SULPHIDE-RICH GAS BACK TO THE REGENERATION SYSTEM FOR TREATING THE CATALYST IN SAID REGENERATION SYSTEM JUST AFTER IT HAS BEEN REGENERATED. 